1. Field of the Invention
Embodiments of the present invention relate generally to reducing the effect of interferers in a radio communication band commonly used in cordless telephone communication. More particularly, embodiments of the present invention relate to an adaptive mechanisms to allocate available bandwidth in the presence of interfering radio signals.
2. Background of the Invention
Cordless telephone products often use the license-free ISM bands for radio communication, such as the 2.4 GHz and 5.8 GHz ISM bands. In addition, numerous other products use these bands for radio communications. Such technologies include for example, 802.11 a/b/e/g, fixed frequency-based systems and wideband systems such as direct sequence spread spectrum systems. The presence of such products leads to interference in communications between the cordless telephone hand piece and its base station. Likewise, cordless telephone communications cause interference with communications occurring in other products operating in these communication bands. This cross-interference often degrades operation in both communication systems.
Cordless telephones can also use frequency hopping techniques for radio communications. Conventional frequency hopping systems use a fixed number of hop channels. The hop channels occupy set areas within the band. Depending on the channel allocation of the systems using the communication band, there may overlap with other systems. Such overlap can cause interference between systems and prevent them from interoperating.
There are a variety of conventional frequency hopping devices including Bluetooth devices, cordless telephones and wireless gaming consoles. Conventional frequency hopping devices have a predefined number of channels and a random hop sequence. The number of channels in the random hop sequence are fixed. Thus, the bandwidth to be used is fixed. Some conventional technologies provide the ability to swap specific channels or drop them from the sequence in the presence of interference. However, the number of useable channels is fixed. The hop sequence is altered only by the number of replacement channels or dropped channels.
Because, the number of channels is fixed, the total usable bandwidth is fixed. As a result, conventional frequency hopping systems cannot adapt to use the free radio frequency (RF) spectrum when it is clear. Moreover, because the bandwidth is fixed, there can be degradation in the frequency hopping system when the free area within the band is less than that for which the hop bandwidth is designed.